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Hi guys, bit of a curly one.....
Been having some issues with my NA 1.8. For the last few months been chasing an erratic idle problem and lack of power in general of the engine.
Basically intermittant fluctuations of the idle when slowing down/coming to a stop. ( only sometimes)
Have changed the throttle body/ISC valve- no result
Injector clean and seal kit- no result
Coolant temp sensor- improved running quite a bit and for a few days thought this was the problem. Drove to Horsham and back on the weekend after replacing temp sensor and it seemed all good, but this morning on the way to work the idle issue came back with a vengance and also I noticed the coolant was overflowing the reservoir tank. Temp gauge normal? It has been using coolant for a while so I've been looking into this as well. No obvious external leak.
Head gasket, radiator, timing belt and water pump done 18mths ago.
Not sure where to go next with this one? Any ideas most appreciated

What fuel have you been using? Filling up at the same place?

O2 sensor been replaced? It's responsible for closed loop idle control so could produce similar symptoms.

Ive just opened my NA6.

while there has always been a bit of oil around it never dripped onto my driveway. It has always used a little bit of oil but nothing serious.
Of late its been using more Oill & water has been diapering .....ever so slowly but more than it used to.

Not saying you have a blown head gasket. Mine wasn't blown as such (OK maybe its blown But I suspect its been like that for some time).....just had oil getting into No 4 cylinder and probably most likely even some coolant.

anyway checking the head gasket is not minor but don't write it off totally.

No 4 looks like it's drenched in oil maybe No3 got some as well

OK maybe I'll rephrase that.

I'm not saying you should take your head off & check.


Check the basics first, air filter,air leaks spark plugs, ignition, 02 sensor and that all the settings are right. Check to see if there is oil in your cool;ant. mabe get your cooling checked eventually. maybe even a compression check before you go considering removing the head
Then once you've run out of options....just because your head gasket was done 18 mths ago. means it was probably fine 18 months ago.

From your previous threads you've mentioned:
coolant leak;
running hot at 100kmh, then returning to normal temp after slowing down; &
sometimes on overrun idle hesitates at 1500 rpm before dropping.

To which can be added:
engine lacking power; &
coolant overflowing from the expansion tank.

Understandably you've tended to look at these individually, but as STM is suggesting, the above issues hint at the requirement for a more holistic approach.

Hey guys thanks for the replies....much appreciated
I was considering changing the O2 sensor next so will do that next. ( I thought this would be a consistent fault and not coming and going? )
Just went and checked the coolant levels now that its cooled down and it is on the full level in the reservoir so maybe I had it overfull yesterday..will find out on the run home I think
Plugs and leads done.
No coolant in oil \or oil in coolant ( that I can see)
Haven't checked ignition ( you mean coil pack? )
Could it be ECU?
I think compression test and coolant system pressure test might have to be done.
The previous thread mentioned by 93 clubman was when I had a blocked radiator leading to head gasket replacement.. Although it ran well after this repair it has always used a bit too much coolant for my liking since then.
Always use 98 fuel but not always from the same garage.

P.S Although I will say it seemed to run really well on the way home from Horsham Saturday...4k rpm all the way home and quite smooth if it had a head gasket?

Ignition
spark
spark plugs
base timing
coil pack.
Leads

If you have a mania or other tyoe CAI.
check for leaves in the filter.
check all the hosing for air leaks. also your PCV valve. and the hose that connects the valve with the intake plenum
check the clamps on the intake system. take it off one by one put each back on conciously

Start from scratch work your way up from the least expensive to detrimental.

ECU, borrow one if you can. you might pick one up for $50-$100 but check all the cheaper options first

Chicane8 wrote:P.S Although I will say it seemed to run really well on the way home from Horsham Saturday...4k rpm all the way home and quite smooth if it had a head gasket?

Mine has been running sweet. no overheating. plenty of power, in no way did it feel tired.
but before you panic about the head gasket.....get all the bits right first.

also check your spark plugs are in tight. I had an issue with cross threading once & eventually it juts came out by itself. It was kind of running a little off before that happened....I just chose to ignore it at the time.
The thread in the block had to be re threaded.
Ive also had the lead not on correctly. even though it runs.....its was just a little off.
check it all.
Get the basics right.

OK guys will keep at it and keep you posted with any progress... Thanks for all the suggestions and ideas ;)

Chicane8 wrote:The previous threads mentioned by 93 clubman was when I had a blocked radiator leading to head gasket replacement. Although it ran well after this repair it has always used a bit too much coolant for my liking since then.

Great to hear it's no longer over heating as this was a bit ambiguous:

Chicane8 wrote:Temp gauge normal?

So over heating can be dropped from following:

93_Clubman wrote:From your previous threads you've mentioned:
coolant leak;
running hot at 100kmh, then returning to normal temp after slowing down; &
sometimes on overrun idle hesitates at 1500 rpm before dropping.
To which can be added:
engine lacking power; &
coolant overflowing from the expansion tank.

Yes that's right it hasn't been overheating since the radiator/ head gasket repair from a while back.
It has used coolant though ever since and I was looking into this before the idle problem popped up.
On the drive home today it didn't blow any coolant out the overflow bottle, so perhaps I did overfill it yesterday.
Maybe the issues are related if there is an internal coolant leak going into combustion or exhaust and fouling the sensor?
The car has done 260,000 and I haven't replaced the O2 sensor so I thought this could be at fault as it seems to run slightly rough in general and down on power a bit, not just the erratic idle...

Chicane8 wrote: head gasket repair ........It has used coolant though ever since

Get a test done for a leaking head gasket. No oil-in-water / water-in-oil / milky oil / etc isn't necessarily a sign that your head gasket is OK. It could be a leak between combustion chamber and a coolant passage.

Not saying that is your "poor running" problem, but it is a problem. Fix that, if it still runs poorly, you know that wasn't it and move on to the next thing.